1. Field of the Invention
The invention relates to internal combustion engines and, in particular, to rotary internal combustion engines and turbine engines.
2. Description of the Related Art
Internal combustion engines are generally characterized by discrete cycles of compression and combustion in time sequential order. In the case of the prevalent four stroke engine, the cycle is subdivided into to functional subdivisions defined by the fuel intake, the compression, the combustion, and the exhaust. In order to avoid pulsations in the power output, these cycles are simultaneously run with a time delay and chronological overlap on a number of combustion chambers that are housed within the same block.
The compression of the combustible fuel (i.e., fuel/air mixture) is typically effected by the same member that is also subject to the power transfer upon the combustion of the fuel. In the context of the Otto cycle, for example, the piston first reduces the volume of the combustion chamber to compress the fuel and then is ejected from the cylinder head by the combustion to drive the output shaft.
Similarly, most prior art rotary engines utilize the rotor to compress the fuel/air mixture in the combustion chamber (e.g. Wankel engine). The rotor is thereby radially asymmetric, it is mounted eccentrically relative to the rotor chamber, or the chamber is not circular. Examples of such engines are found in U.S. Pat. Nos. 4,075,981 to Durst, 3,301,233 to Dotto et al., and 3,782,110 to Kobayashi, respectively. An alternative design was recently proposed in U.S. Pat. No. 5,429,084 to Cherry et al. where the rotor and the chamber are radially symmetrical and the combustion chambers are instead formed laterally on either sides of the rotor. Several vanes move axially to close off the combustion chambers. The compression "stroke" is effected by the narrowing of the combustion chamber during the angular displacement of rotor relative to the rotor housing (the stator) and the reduction in chamber volume effected by the respective vane.
Various engines have been proposed with concentric rotors. Typically, such engines have a flat-cylindrical or doughnut-type housing and a central rotor that drives and output shaft or input shaft. For example, U.S. Pat. No. 2,390,880 to Harrold teaches a steam engine with a central rotor that carries two radial vanes. The vanes pass by two kidney-shaped turning valves.
U.S. Pat. No. 1,268,794 to Harris et al. teaches a convertible engine/pump. Turning valves mesh with teeth at the grooves of a periphery of the rotor and several pistons mesh with kidney-type indentation in two turning valves. The Harris et al. engine provides for two rotors and the pistons are offset between the two rotors so as to obtain a smooth pulse distribution in the timing of the explosions in the combustion chambers.
A system with separate combustion chamber and fuel pressurization was disclosed in British Patent Specification 265,659 to Bernhard. Fuel is pressurized in a compressor and the pressurized fuel is fed from the pump to the engine through a port assembly. A single piston and a single abutment define the combustion chamber.
The prior art engines have in common that fuel is cyclically combusted and the power output, as a result, is subject to pulsating output peaks. Sporadic air and fuel injection is more complicated and difficult to measure than continuous or nearly continuous injection. Most of the prior art engines, furthermore, contain a plurality of reciprocating parts which are subject to constant momentum changes and attendant energy losses. Even the rotary Wankel engine, for instance, is not a completely round system since its excentric rotor is subject to lateral displacement which causes further mechanical losses.